Weight relief and fluid control on drill pipe



J. A. ZUBLIN April '21, 1931.

WEIGHT RELIEF AND FLUID CONTROL ON DRILL PIPE Filed April 22. 1929 4 7- rare/vex Patented Apr. 21, 1931- JOHN A. ZUBLIIN', 0]? LOS ANGELES, CALIFORNIA I WEIGHT RELIEF AND FLUID CONTROL ON DRILL PIPE Application filed April 22,

tion may be readily understood I shall briefly refer to the well-drilling industry, in which my invention is useful. According to present practice, the drill pipe is extended into the well, there being a bit at the lower end of the drill pipe and there being rotatthe drill pipe where the drill pipe extends through the floor of. the derrick. A swivel head is connected to the upperend of the drill pi e by which the drill pipe is supportthe well through the drill pipe. This rotary mud passes through openings in the bit and passes upward through the well around the drill pipe, carryingthe cuttings to the sur-' face of the ground, preventing. caveins, and floating the drill pipe away from the wall of the well. i

It is common practice to drill wells over. six thousand feet deep. In view of the enormous torque which must be transmitted through the drill pipe to the bit it is necessary to make the walls of the drill pipe heavy enough to withstand such torque. According to the ordinary method of drilling, a portion of the weight of the .drill pipe is supported by the bit in order that there may be acuttin action. The remaining portion of the weig t of the drill piie is carried by the swivel head .of the derric Because of the eat weight of the drill pipe which must be argely supported by the swivel head there is a tendency for the drill pipe to separate at the tool joints. There is also a possibility thatithe elastic limit of the pipe may be ex-- ceeded. For example we may assume that the elastic limit of the metal'is reached. If

the bit sticks in the wellit is necessary to lift upward on the upper end of the drill pipe to free it. Since the drill pipe' is already at ing means such as a rotary machine engaging ed and y which rotary mud is-pumped into 1929. 8 Serial No. 357,010.

its elastic the additional force to raise of and results in a breakage. As wells are drilled deeper this tendency to separate increases. It 'is an object 'of my invention to rovide a drill p1pe which is partly or fullyfioating so that it is not necessary to support most of the weight of the drill pipe fr 111 the upper end thereof. The advantage (3f a construction embodying this object is that the tendency forthe drill pipe to pull apart will be relieved to the extent that there will be no danger of such a separation occurring.

As pointed out heretofore it is ordinary practice to circulate mud through the Well. At adepth of about six thousand feet the pressure per square inch of the rotary mud is around threethousand pounds. So long as the pressurewithin the drill pipe and outside-the drill pipe is in balance there is no preponderance of forces tending to collapse or disrupt the drill pipe. If, however, it is attempted to form gas chambers in the drill pipe in order to obtain buoyancy it is necessary'for the gas chambers tov contain a gas under a pressure of substantially the same pounds per; square inch" as the external rotary mud. Unless there is this balance of pressure, there will be collapsing forces on the drill pipe.

It is an object of my invention to provide a drill pipe having gas chambers or flotation chambers in which t'e pressure is substantially the same as t e external pressure on the drill pipe. I 1 The pressure of the rotary mud increases in a ratio directly proportionate to the increase in depth of the well; therefore it will be seen that at the lower end of the drill pipe thepressure in the gas chambers must e greater than the pressure in the gas chambers near the upper end. of the well, 1n order that a balance with the external pressure of the rotary mud may be obtained. the length of p1pe is of such aweight that It is an object-of my invention to provide a drill pipe in which the gas chamber pressure is automatically malntained substantially the same as the external pressure at a corresponding" level.

, the drill pipe exceeds .the elastic l'nm'tthere- It is necessary upon commencing drilling operations with the drill pipe of my invention to fill the gas chambers with gas and it is further necessary to maintain these gas chambers filled with compressed gas.

It is one of the objects of my present invention to provide a method ofsupplymg gas to the gas chambers and of maintaining the desired quantity of gas in the various gas chambers during the operation of the drill p %Vhen the rotary mud is under high pressure every reciprocation of the pump plunger causes a rather severe vibration or pulsations. This is due to the fact that the rotary mud is an inelastic fluid. It is these pulsations that usually cause a breakage of the flexible hose of the apparatus. It sometimes happens that the openings in the bit through which the rotary mud passes will become clogged, and the pressure in the drill p pe will instantaneously build up to such a point that the rotary hose will be burst.

It is an object of my invention to provide the drill pipe with one or more chambers filled or partly filled with a compressible fluid which acts as a shock absorber or pulsation absorber.

When this feature of my invention 15 embodied in the drill pipe there will be no severe pulsations and when the openings in the bit are clogged, pressure will not instantaneously build up to a pressure greater than the rotary hose can handle but will gradually build up. As the pressure builds up the pump will operate slower, this acting as a signal to warn the operator that something is wrong. This will enable the operator to shut down the pump before the rotary pump has burst or any other damage has occurred.

Another of my objects is to provide a novel tool joint for drill pipe which facilitates the use of an inner tube which forms the gas chambers.

Other objects of my invention reside in the details of construction of the preferred form of my invention. In, the following description which presents the preferred form of my invention these various other objects will be made manifest.

Referring to the drawings in which my invention is illustrated: I

Fig. 1 is a utility view showing the drill pipe of my invention and showing the apparatus necessary for the performance of the method of my invention.

Fig. 2 is a section through a portion of drill pipe which incorporates the features of my invention.

Fig. 3 is a section taken on the line 33 of Fig. 2.

Referring to the drawing in detail, the numeral 11 represents a well which is being drilled by means of a bit 12 secured to the lower end of a drill pipe 14 which incorporates the features of my invention. This drill pipe 14 consists of lengths of pipe 15 secured together b tool joints 16. Connected to the upper end 0 'the drill pipe 14 is a swivel head 17, by means of which a portion of the weight of the drill pipe may be supported. The swivel head 17 has a gooseneck 18 to which aflexible hose 19 is secured. The flexible hose 19 is connected to a stand pipe 20 which is also connected to a slush pump 21. A branch pipe 22 having a valve 23 is connected to the stand pipe 20, this branch pipe 22 being also connected to a gas supply means, such as an air compressor 24.

The drill pipe 14 is rotated by means of a rotary machine 25 supported on the floor of a derrick 26.

In Figs. 2 and 3 in which the details of the drill pipe 14 are illustrated, the tool joint 16 consists of a primary part 27 and a secondary part 28. The primary part has a threaded pin 29 which is screwed into a threaded socket or box of the secondary part. The upper end of the primary part is provided with an internally threaded flange 31 into which the lower end of a length of pipe 15 is screwed, and the secondary part 28 has a lower internally threaded flange 32 into which the upper end of a length of pipe 15 is screwed.

The secondary part 28 has a threaded opening 35 connecting to the box thereof and threaded into this opening 35 is an upper threaded end 36 of a tube 37. The primary part 27 is provided with a passage 38, the upper end 39 of which is slightly enlarged to receive a lower end 40 of the tube 37. The external diameter of the tube 37 is smaller than the diameter of the enlargement 39-and therefore an annular space 41 is formed around the lower end of the tube 37. A plurality of openings 43 are formed in the lower end of the tube 37, as shown.

The tube 37 provides a passage 44 which cooperates with the passage 38 to provide a continuous passage from the swivel head 17 to the bit 12'. Through this passage rotary mud passes from thesurface of the ground to the bottom of the well. In each length of pipe 15 surrounding the tube 37 therein is an annular gas chamber 46. The upper end of the gas chamber 46 is sealed by reason of the upper end of the tube 37 screwing into the threaded opening 35. The lower end of the gas chamber 46, however, is in communication with the passage 44 by reason of the .openings 43 and the annular space 41.

Inthe drill pipe 14 incorporating the invention just described every section of the drill pipe may be formed as shown in Fig. 2. It may be satisfactory, however, to construct the drill pipe so that only certain sections are provided with the gas chambers 46, ac-

cording to the needs of a particular eondition and according to the weight of the drill pipe which is being used. It may be laid well around the drill pipe 14 he will know down as a rule, however, that suficient gas' chambers 46 should be provided in order to relieve the weight which must be supported by the swivel head 17 to the extent that there will be no danger of the joints of drill pipe being separated.

After the drill pipe has been installed in the well as illustrated in Fig. 1, the slush pump 21 is set into operation, in order to force rotary mud through the drill pipe to the bit 12. The air compressor 23 .is also set into operation and the valve in the branch pipe 22 is opened and a quantity of compressed as is passed into the stream of rotary mud fiowing through the stand pipe 20. This rotary mud having the compressed gas mixed therewith passes downward through the passage of the drill pipe. Due to the difference in specific gravities of the rotary mud and the compressed gas there is always atendency tor the compressed gas to rise relative to the rotary mud. The rotary mud and compressed gas pass downward through the passage as indicated by arrows 50 in Fig. 2.

The as bubbles have a tendency of passing throug the openings 43 and through the annular space 41 and into the gas chamber 46, as indicated by arrows 51 and 52. The gas, therefore, is caused to fill the gas chamber 46, the rotary mud assuminga level substantially asdndi-cated at 54 in Fig. 2. As

previously pointed out the rotary mud passes from the bit 12 and upward through the well around the drill pipe 14 to the surface of the ground. When the operator observes that bubbles ofcompressed gas are rising in the that the gas chambers 46 have been filled with gas. The operator will then close the valve in the branch line 22 and shut down the compressor 24. The gas chambers may also-be filled by operating the air compressor24 without the slush pump 21. The gas is forced downward through the drill pipe, filling all of the gas chambers 46. When the gas chambers 46 have been filled, the gas will pass from the openings in the bit 12 and upward through the well around thedrill pipe. The operator will then know that'the chambers are filled and he will then put the slush pump 21 into operation. It is desirable at certain intervals to again start upv the compressor 24 and open the valve in the branch pipe 22 so that if leakages have. oc-

curred in any of the chambers 46 they may 1 be refilled with compressed gas.

Due to the difference in the specific weight of the compressed as and the rota g mud, buoyancy is provi ed, which will oat or support a portion of the weight of the drill pipe, thus relieving the weight'at the swivel head 17. This is effective in reducing the tendency for the sectionsof the drlll plpe to be separated. 5

Due to the fact that the gas chambers 46 of the drill pipe 14 are in communication withthe passage through the drill pipe 14 the gas in the gas chambers will be maintained at the same pressure as the rotary-mud in the passage at that level. The pounds pressure per square inch of the rotary mud in the passage is the same as the pounds pres sure per square inch of the rotary mud around the drill pipe. Therefore, the pressures in the passage and the chambers 46 and surrounding the drill pipe will be the same. In other words, these pressures are in balance so that there are no forces tending to collapse or disrupt either the length of pipe 15 or the tube 37 which forms a part of each section of the drill pipe 14. a

As pointed out in the objects of this in vention the gas chambers act as shock absorbing means and absorb the pulsations of the slush pump 21. This prevents severe vibrations and severe strains from being imposed on the parts of the apparatus and eliminates knocking in the slush pump. Should the openings in the bit 12 become clogged the pressure of the rotary mud will be gradually raised. This is due to the fact that the bodies of gas in the gas chambers 46 will gradually be compressed to a greater extent. As the pressure increases the slush pump will labor harder and the operator will know that something has occurred which is increasing the pressure in the rotary mud systerm. The slush pump may be shut down before the rotary hose has been burst. This done to the not only avoids damage being apparatus but prevents any injury to workmen on the derrick floor.

I claim as myinvention:

1. A method of rendering buoyant a column having a passage and a chamber connected'at its lower end to said passage, said method consisting in: passing a rotary mud and a gas through said passage, said gas flowing into and being trapped in said chamber, and said rotary mud passing through said passage.

2. In apparatus for drilling wells, the combination of: a drill pipe adapted to be extended into a. well; a pump for delivering an incompressible'fluid under pressure to said drill pipe; means for pumping a gas into said drill pipe; and means embodied in said drill pipe for absorbing the pulsations of said pump. 1

3. In apparatus for drilling wells, the combination ofaa drill pipe adapted to be extended into a. well; a pump for delivering an incompressible fiuid under pressure to said drill pipe; means for pumping a gas intosaid drill pipe; and walls forminga compressible gas chamber in said drill pipe, said compressible as chamber containing a compressible as adapted to absorb the pulsations of said pump.

4. In well drilling apparatusf the combination or: a drill pipe having walls forming air chambers and a fluid passage, said air chambers communicating With said fluid passage at points below their upper ends; means for forcing a drilling fluid through said fluid passage; and a pump for forcing a gas into said fluid passage.

5. In well drilling apparatus, the combination of: a drill pipe having Walls forming air chambers and a fluid passage, said air chambers communicating with said fluid passage at points below their upper ends; a swivel at the upper end of said drill pipe; a tubular member connected with said swivel for the introduction of fluids into said drill pipe; a liquid pump connected to said tubular member; and a gas pump connected to said tubular member.

In testimony whereof, I have hereunto set my hand at Los Angeles, California, this 16th day of April, 1929.

JOHN A. ZUBLIN. 

